Project Summary Autophagy, the process that mediates degradation of intracellular constituents in lysosomes, is an essential component of the cellular quality control systems and of the cellular response to very different stressors. This project focuses on this role of different autophagic pathways as part of the cellular response to stress and aims to elucidate the contribution that the age-dependent changes in autophagy have on the inadequate response to stress in old organisms. During the previous period, we have identified a novel role of autophagy in the cellular response against lipotoxicity (with P4) and genotoxicity (with P3) that we will now explore in more detail in the context of aging, a condition in which we have identified a malfunctioning of two types of autophagy, macroautophagy (MA) and chaperone-mediated autophagy (CMA). In addition, we will incorporate analysis of endosomal microautophagy (eMI), an autophagic pathway that we identified in collaboration with P2, to our study. The overall goal of this proposal is 1) to elucidate the contribution of the impairment in autophagy with age to the functional deterioration and inability to orchestrate an efficient stress response in aging, 2) to understand the molecular mechanisms behind compensation among different autophagic pathways and 3) to devise interventions that could help overcome the autophagic failure in aging. The three original specific aims will be continued/expanded to address: 1) What happens to autophagy during stress? In this period we will focus on three stressors: lipotoxicity, proteotoxicity, and genotoxicity; 2) What happens if autophagy does not work under stress conditions? We will utilize the recently generated conditional mouse models with compromised CMA and the ones with compromised MA to study their response to the three stressors and analyze the molecular basis of possible compensatory mechanisms among autophagic pathways; 3) Can we improve the response to stress by repairing autophagy? We will analyze the possible beneficial effect in the organ-specific response to stress of upregulating CMA by using genetic interventions and by continuing the development of chemical modulators of CMA. Relevance: Alterations in the ability to orchestrate an efficient response to stress underlie the basis of important age-related diseases. The studies in this project may provide the conceptual basis and tools for future efforts aimed at manipulating autophagy to improve the response to stress in the elderly and delay the onset of age-related diseases.